This invention relates to the production of a mixture of silicoformic epoxy and silicic epoxy polymers which will be referred to as silicic epoxy polymers for the purposes of this Application.
Silicoformic acid and hydrated silica used in this process may be produced by chemically reacting a dry granular alkali metal metasilicate with a concentrated mineral acid or a hydrogen containing salt, as disclosed in my U.S. Pat. Nos. 3,993,737, filed by David H. Blount. Silicoformic acid may be produced by other methods as those disclosed in U.S. Pat. Nos. 3,674,430 and 3,937,782.
The silicoformic acid as produced in my U.S. Pat. Nos. 3,956,466 and 3,962,111 and which was used in this invention, was analyzed. It was found to contain mainly silicoformic acid (H.SiO.OH) and hydrated silica (SiO.sub.2.xH.sub.2 O). I know of no method to separate the two; both are a white granular compound. The silicoformic acid contains Si--H bonds.
The said silicoformic acid was analyzed by Infrared Analysis, using the Infrared KBr disc method. It was found to be similar in nature to the Mallinckrodt's hydrated silica, SiO.sub.2.xH.sub.2 O, except for the presence of Si--H bonds which gave a definite absorption peak at 615 cm.sup.-1. This is attributable to one of the varieties of Si--H bonding characteristics, as found and identified in Beckman Instruments Far IR Vibrational Frequency Correlation Chart. The Mallinckrodt's hydrated silica has a molecular weight of 60.09xH.sub.2 O. An aqueous suspension of the silicoformic acid will reduce an aqueous silver nitrate solution which gives further evidence that Si--H bonds are present.
The silicoformic acid was analyzed but using hydroflouric acid to remove the silicon dioxide, and the dry compound contained about 90% silicon dioxide, 5% water and 5% salt. The compound has a high melting point estimated at 1650.degree. C. The melted sample fuses into a glass-like material, clear in appearance.
The silicoformic acid and hydrated silica mixture is not soluble in any common organic solvents but is readily soluble in dilute alkali metal hydroxide aqueous and polyol solutions.
The molecular weight was determined by the boiling point elevation of a 6N NaOH solution and indicated a molecular weight of 78 .+-. 25 gm/mol. This type of reactive solution normally changes the molecular species. However, this would indicate the absence of a polymeric form of silicate. It may indicate a possible formula of H.sub.4 SiO.sub.3 (orthosilicoformic acid) and H.sub.3 SiO.sub.3 (metasilicic acid).
The silicoformic acid compound has the chemical properties of an acid and rapidly reacts with alkali compounds. The silicoformic acid compound is an acid, has Si--H bonds and is similar to hydrated silica in molecular weight; therefore, it has a chemical formula of H.SiO.OH.xH.sub.2 O.
The silica hydrate mixed in with the silicoformic acid will also react with epoxy compounds to produce epoxy silicate polymers.
While a wide variety of epoxy compounds and polymers have been produced for a number of diverse applications, none have the unique properties possessed by the compounds of this invention. Epoxy silicoformate polymers and epoxy silicate polymers may be used as molding materials, as coating agents, in dispersions, as adhesives, as fillers, in casting applications, as prepolymers, as impregnates, in rubber-like materials and may be copolymerized with other reactants. They may also be used as intermediates in the production of further compounds.